eap Mailing List: EAP-AKA Key derivation

[Thomas Otto (t.otto]

Hi all,

EAP-AKA uses the DSS key derivation function (KDF) to derive
export keying material.

Although the draft describes the KDF briefly (see below), I would
not be able to ... say implement this function. Rather I would have
to look in NIST publication what the SHS actually is ... :-(

So, does anyone know why this burden is in EAP-AKA?

Thomas




__________________
   Step 1: Choose a new, secret value for the seed-key, XKEY

   Step 2: In hexadecimal notation let
       t = 67452301 EFCDAB89 98BADCFE 10325476 C3D2E1F0
       This is the initial value for H0|H1|H2|H3|H4
       in the FIPS SHS [SHA-1]

   Step 3: For j = 0 to m - 1 do
         3.1 XSEED_j = 0 /* no optional user input */
         3.2 For i = 0 to 1 do
             a. XVAL = (XKEY + XSEED_j) mod 2^b
             b. w_i = G(t, XVAL)
             c. XKEY = (1 + XKEY + w_i) mod 2^b
         3.3 x_j = w_0|w_1